Antimicrobial effect of the extracts of a ginseng by-product produced by subcritical water extraction, nisin, and their combination against Listeria monocytogenes in milk products

The aim of the study was to investigate the antimicrobial action of the extract of ginseng by-product (1.0, 2.0, and 4.0%) produced by subcritical water extraction (SWE), nisin (125, 250, and 500 lU/ml), and their combination in milk products at 4°C. The addition of the SWE of the ginseng by-product (1.0,2.0, and 4.0%) resulted in no change in the initial number of Listeria monocytogenes in whole and low-fat milk during storage. Nisin at concentrations of 125,250, and 500 lU/ml was shown to decrease numbers of L. monocytogenes in skim milk. In contrast, the control (without the SWE of ginseng by-product or nisin) showed an increase in the number of L. monocytogenes. In addition, the combined addition of the SWE of ginseng by-product at 1.0 or 2.0% and nisin at 125 or 250 lU/ml showed a synergistic activity against L. monocytogenes. In particular, in skim milk, when ginseng extract at 2.0% was added with nisin at 500 lU/ml, L monocytogenes could not be detected after 1 day of incubation. This study demonstrates the synergistic antimicrobial effect of the combination with the SWE of ginseng by-product and nisin and indicates the potential of this combined treatment in food processing.